1. Field
The present disclosure relates to semiconductor devices, and more particularly, to high electron mobility transistors (HEMTs) having a reverse diode gate or a depletion structure.
2. Description of the Related Art
As communication technologies have continuously developed, electronic devices for high frequency bands have been actively studied. In particular, field effect semiconductor devices such as high electron mobility transistors (HEMTs) have drawn attention as power electronic devices to be used in high frequency bands.
A HEMT may include a heterostructure which is formed by adjoining semiconductor material layers having band gaps different from each other. Of the semiconductor material layers, a semiconductor material layer having a large band gap performs as a donor. Since the heterostructure includes the semiconductor material layers having band gaps different from each other, a 2-dimensional electron gas (2DEG) layer may be induced in the semiconductor material layer having a smaller band gap than the other, and thus, mobility of electrons may be increased.
The HEMT may be used for increasing the mobility of electron carriers and may be used as a high pressure-resistance transistor in a power electronic device as well. The HEMT includes a semiconductor having a wide band gap, for example, a compound semiconductor, and may have a relatively large high breakdown voltage. Therefore, the HEMT may be used in high voltage application fields.
In general, in semiconductor devices that include silicon, a high source resistance may be generated due to low electron mobility. Therefore, studies have been conducted to use a group III-V semiconductor compound in HEMTs. In particular, since GaN compounds have a relatively large band gap and a high electron saturation velocity, and are chemically stable, they have drawn attention as a material for HEMTs. Accordingly, studies have been actively performed to use GaN compounds in a high temperature, high output, and high frequency electronic device.